What is the difference between manual and automation testing?

It is simple. In manual testing, a person does all the work. Like a real user. They click the buttons. They type in the forms. They check with their eyes if everything is okay. This is good for finding problems with the user experience. But it is very slow. It is also easy to make mistake if you do the same test many times.

With automation testing, a computer does the work. A person writes a script, like a code. The computer then runs this script to do the test very fast. This is perfect for tests you must repeat many times. For example, after you change some code. But the computer does not have eyes. It cannot tell you if a color is ugly. It only checks what the script tells it.